CB750K5-K6 '75-'76 SOHC KeiHin 657B and 086A
All of the CB750 SOHC carbs made from '69-'76 look similar, but they are VERY diverse. You have to pay close attention to the specific version to correctly rebuild and the bike they are currently installed. Even the motors can be swapped, so this can even include the '77-'78 years. They are found to be interchanged and very mixed-up so just replicating current parts installed, is a recipe for disaster.
This set is the KeiHin 657B and is basically the same as the previous '73-'74 657A, but now the idle adjust is on the right side of the carbs due to the petcock changing to the left side of the gas tank '75 and later. Also these carbs came with the gold colored zink on most of the steel brackets and linkage. Typically the 657B is on '75 and early '76, and 086A is on '76 CB750K's and '76 CB750F1 Super Sports.
Keep in mind that from '71-'76 you can physically change bodies and throttle risers in almost any combination. It is rather rare to find the carbs to be 100% correct. The main differences to consider is what side of your tank the petcock is on so your carbs have access to the idle adjust that will be on the opposite side as the petcock, and always build the carb body to the id number as called for on that body.
